What is the role of oxygen in a backyard pond during winter?

Oxygen is crucial in a winter pond to support fish respiration and beneficial bacteria that break down waste. Ice cover reduces natural gas exchange, risking low oxygen levels that can stress or kill pond life. Using aerators or de-icers to keep an opening in the ice maintains oxygen circulation. Adequate oxygen prevents toxic gas accumulation, supports fish health, and preserves biological balance during cold dormancy periods.